This dissertation presents a technique for recovering translational motion parameters using two simplified planar compound-like eye schemes, namely a parallel trinocular system and a single-row Superposition-type Planar Compound-like Eye (SPCE). In the parallel trinocular scheme, a least squares estimation algorithm is developed for recovering the translational motion parameters. The proposed approach resolves the matrix singularity problem encountered when attempting to recover motion parameters using a conventional binocular scheme. To further reduce the computational complexity of the motion estimation process, a compact closed-form scheme is also proposed to estimate the translational motion parameters. The closed-form algorithm not only resolves the matrix singularity problem, but also avoids the requirement for matrix manipulation. As a result, it has a low computational complexity and is therefore an ideal solution for performing motion estimation in complex, real-world visual imaging applications following an initial image filtering process. The performance of the closed-form algorithm is evaluated by performing a series of numerical simulations in which translational displacements of various magnitudes in three-dimensional space are recovered in both noise-free and perturbed environments. In general, the results demonstrate that the translational motion parameters can be reconstructed with a high degree of accuracy provided that the motion in the depth direction is limited to small displacements only. Having developed a motion estimation scheme for a parallel trinocular system, additional charge coupled device (CCD) cameras are added in the horizontal direction to create a single-row SPCE. Translational motion models for the SPCE are then constructed by stacking the optical flow equations in the horizontal direction. The ego-translational parameters are then extracted using a simple least squares estimation algorithm. The simulation results reveal that the introduction of additional cameras to the machine vision system ensures an excellent motion estimation performance without the need for filters of any kind even when the viewing field is characterized by significant noise or the CCD deployment within the SPCE configuration has a non-uniform distribution. Overall, the parallel binocular scheme and single-row SPCE configuration presented in this dissertation demonstrate a high degree of robustness toward noise and enable the motion estimation process to be performed in a rapid and computationally efficient manner using a simple least squares approximation approach. Whilst science can not realistically hope to improve upon the visioning capabilities found in the insect world, the techniques presented in this dissertation nonetheless provide a sound foundation for the development of artificial planar-array compound-like eyes which mimic the mechanisms at work in biological compound eyes and attain an enhanced visioning performance as a result.

The continuously increasing demand for connecting electric grids with remote renewable energy sources such as wind power and photovoltaic cells has rekindled interest in high voltage direct current (HVDC) multi-terminal networks. Although HVDC networks have numerous benefits, their adoption relies entirely on the availability of HVDC circuit breakers which, compared to traditional alternating current circuit breakers, have to operate in a time frame of milliseconds. This thesis deals with the design of ultra-fast electro-mechanical actuators based on the so-called Thomson coil (TC) actuator. The simulation of a (TC) actuator constitutes a multi-physical problem where electromagnetic, thermal, and mechanical aspects must be considered. Moreover, it is complex since all those variables are co-dependent and have to be solved for simultaneously. As a result, a multi-physics simulation model that can predict the behavior and performance of such actuators with a high degree of accuracy was developed. Furthermore, other actuator concepts were also investigated and modeled in light of searching for a drive with a superior efficiency. The theory behind the force generation principles of two different types of ultra-fast electromechanical actuators, the TC and the double sided coil (DSC), were compared by the use of static, frequency, and comprehensive transient multi-physics finite element simulation models. Although, simulation models serve as a powerful tool for modeling and designing such state of the art actuators, without validation, they are weak and prone to errors since they rely on approximations and simplifications that might not always hold. Therefore, a prototype was built in the laboratory and the model was validated experimentally. Finally, it is important to note that the drives in this thesis are intended to actuate metallic contacts. As such, their behavior and performance upon mechanical loading was studied. Furthermore, some scaling techniques were applied to boost their performance and efficiency. / <p>QC 20130422</p>

The continuously increasing demand for clean renewable energy has rekindled interest in multi-terminal high voltage direct current (HVDC) grids. Although such grids have several advantages and a great potential, their materialization has been thwarted due to the absence of HVDC breakers. In comparison with traditional alternating current (AC) breakers, they should operate and interrupt fault currents in a time frame of a few milliseconds. The aim of this thesis is focused on the design of ultra-fast electro-mechanical actuator systems suitable for such HVDC breakers.Initially, holistic multi-physics and hybrid models with different levels of complexity and computation time were developed to simulate the entire switch. These models were validated by laboratory experiments. Following a generalized analysis, in depth investigations involving simulations complemented with experiments were carried out on two of the sub-components of the switch: the ultra-fast actuator and the damper. The actuator efficiency, final speed, peak current, and maximum force were explored for different design data.The results show that models with different levels of complexity should be used to model the entire switch based on the magnitude of the impulsive forces. Deformations in the form of bending or elongation may deteriorate the efficiency of the actuator losing as much as 35%. If that cannot be avoided, then the developed first order hybrid model should be used since it can simulate the behavior of the mechanical switch with a very good accuracy. Otherwise, a model comprising of an electric circuit coupled to an electromagnetic FEM model with a simple mechanics model, is sufficient.It has been shown that using a housing made of magnetic material such as Permedyn, can boost the efficiency of an actuator by as much as 80%. In light of further optimizing the ultra-fast actuator, a robust optimization algorithm was developed and parallelized. In total, 20520 FEM models were computed successfully for a total simulation time of 7 weeks. One output from this optimization was that a capacitance of 2 mF, a charging voltage of 1100 V and 40 turns yields the highest efficiency (15%) if the desired velocity is between 10 m/s and 12 m/s.The performed studies on the passive magnetic damper showed that the Halbach arrangement gives a damping force that is two and a half times larger than oppositely oriented axially magnetized magnets. Furthermore, the 2D optimization model showed that a copper thickness of 1.5 mm and an iron tube that is 2 mm thick is the optimum damper configuration. / <p>QC 20150422</p>